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H. D. BURNBTT 8v S. E. DOANE.

l l INGANDESGENT LAMP AND METHOD 0I' MANUFACTURING SAME.A

No. 516,800. 1"1.|.e11ced-lVIa.r.'20,V 1894.

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HENRY D. BURNETT, OF LYNN, AND SAMUEL E. DOANE, OF SWAMPSCOTT,

ASSIGNORS TO THE GENERAL ELECTRIC COMPANY, OF BOSTON, MASSA- oHUsETTs.

INCANDESCENT LAMP AND METHOD OF MANUFACTURING SAME.

SPECIFICATION forming part-of Letters Patent No. 516,800, dated March 20, 1894.

Application filed Marchl', 1893. Serial No. 4:6 5,506. (No model.)

'To a/ZZ whom it may concern:

setts, citizens ofthe United States, have invented certain new and useful Improvements in Incandescent Lamps and Methods of Manufacturing the Same, of which the following is a specication.

Our invention relates to incandescent electric lamps and their manufacture, more particularly to the manufacture of the glass part of such lamps,including their exhaustion and the connectin gto them of the leading-in wires which convey current to the inclosed filament; and has for its objects to cheapen the labor cost of such lamps and to improve their appearance by giving them a smooth contour, pear-shaped spherical orglobular shaped, having no protuberance upon the body of the bulb. To these ends we change the location of the ordinarytubular connection,providingforexhausting the air from the globe. This tubular connection is generally made upon the round surface of the globe opposite the middle or bend of the filament; a small` glass tube being usually sealed to this part of the lamp, the operation being known among manufacturers as tubulating It is one of the operations requiring skill and experience on the part of a gas blower to prevent the collapse or deformation of the bulb by improper heating or by unskilled manipulation after it has been heated. It also requires dexterity to connect this small exhaust tube so that the protuberance upon the lamp bulb, when the lamp is sealed oft", shall be exactly central. These operations requiring delicacy and skillv (and being therefore expensive), we avoid by our improved process; moreover, the objectionable protuberance upon the bulb is not found and the lamp has a smooth surface. To attain these ends, We seal off`the lamp from its base or neck. We are aware that this has been proposed and to some extent carried into operation; but our invention differs from all former methods of performing this operation, with which we are acquainted as will be more fully explained hereinafter.

Figure l is a longitudinal vsection of a piece of tubing employed in our invention. Fig.2

Vis a similar section of the same piece of tubing after the second step of our process. Fig. 3 is a similar section of a smaller piece of tubing to be placed inside of the rst; Fig. 4, a similar section of the two tubes with tho leading-in wires in place; Fig. 5 a View of an instrument used in sealing the leadingin wires into the glass; Fig. 6 an Aelevation of the parts shown in Fig. 4. after the seal has been made; Fig. 7, a representation of a lamp bulb before the Wires have been inserted; Fig. S, a representation of the lamp completed and -sealed o ready for insertion in its socket; Fig. 9, across section upon the line 9, 9, of Fig. 4, and Fig. l0 a representation of the exhausting tube or spider showing one of our improved lamps after the exhaustion has been completed, attached thereto and in process of being separated therefrom.

Referring by letter, A is a short piece of tubing of suitable size, constituting the lilarnent support; this piece of tubing being softened by heat, it is spread out at one end into a flared shape, or in other Words, a liange marked a, Fig. 2, is lformed upon it.

B is a smaller piecek of tubing through which the lamp is exhausted.

C is the bulb into which the parts shown in Fig. 6 are to be sealed at the point K, as shown in Fig. 8.

T is the tube leading to the air pumps and c' shows the point at which the tube is sealed off by the gas .iame as shown in Fig. 10.

The operation is conducted as follows: After the flange a is formed upon the tube A the small tube B is placed inside it, as shown best in Fig. 4., and the leading-in wires for carrying the filament are passed between the two tubes; the tubes are then softened by heat at the part marked H, and compressed or welded together by the pliers shown/ingFig. 5, thus sealing in the leadingin wires effectively, the pliers being provided roo with a cut-away portion, c, in their jaws to prevent the collapse of the interior tube B; at this stage of the operation the parts appear as in Figs. 6 and 7. The tube A being then inserted into the lamp bulb the flange a and the neck of the bulb are softened in the gas flame in the usual manner and fused together at the point K making a tight joint, butstill leaving the tube B open to the interior of "the lamp. This tube is then sealed to one of plug the tube full of any comparatively infusible or refractory material which may suftice to hold it open. use asbestus thread or asbestus pastes, or graphite held together by any cement which will disintegrate under heat allowing the graphite to be shaken out;` or various combinatons of calcareous paste, such as plaster of paris or chalk which under the influence of the heat will soften so they may be shaken or washed out. y

In `the commercial practice of our invention wehave found it advisable to have a clutch for holding centrally a glass tube and an interior glass tube, together with the leading-in wires, two or more as may be desired; the clutch of course being mounted so that it may be revolved at pleasure. We also provide means for inserting the rod ot' carbon or metal as before referred to, in some cases keeping the rod stationary, while the glass revolves, or in others revolving the rod and keeping the glass stationary; we may also advance or retreat the rod as may be found desirable.

We do not herein illustrate or claim the arrangement of machine adapted to do this work; but We reserve the right by any future application to claim such novelty as may be found in the construction referred to.

We are aware that lamps may be exhausted through the base in many ways; we therefore do not claim such a method broadly, but

In lieu of` the solid substance thus described, we may For this purpose we may What we claim, and wish to protect by Letters Patent ofthe United States,is--

1. The method of making incandescent lamps herein set out, which consists in placing theleading-inwires between an inner and outertube,softeningandcompressing theends of said tubes so as to seal in the wires, then sealing the outer tube to the neck of the lamp, exhausting the lamp by means of the inner tube, and nally sealing off the inner tube.

` 2. The method of making incandescent lamps herein set out, which consists in placing the leading-in wires between inner and outer concentric tubes, welding together the upper ends of the tubes so as to seal in the wires, sealing the outer tube to the neck of the lamp, exhausting the lamp through the inner tube and finally sealing off such inner tube.

3. The method of making incandescent lamps herein set out, which consists in forming a flange upon a piece of tubing, placing inside of such tubing a smaller tube, inserting leading-in Wires between the tubes, sealing the tubes together around the wires while maintaining the innertnbe open, sealing the flange upon the outer tube to the base of the bulb, exhausting the lamp through and sealing off the smaller tube.

4. The method of making incandescent lamps herein set out, which consists in filling a tube with refractory material, placing outside thereof a second tube, placing leading'- in wires between the tubes and sealing them together, removing the refractory material, sealing the outer tube to the neck of the lamp, exhausting the lamp through and then sealing off the inner tube.

5. The method of making an incandescent lamp herein set out, which consists in forming a ilange upon a piece of tubing, placingin such tubing another tube containing refractory material, placing leading-in wires be- 95 tween the tubes and sealing them together, removing the refractory material, sealing the flange to the base of the bulb, exhausting the lamp through and sealing off the inner tube.

In `witness whereof we have hereunto set roo i our hands this 14th day of March, 1893.A

HENRY D. BURNETT. SAMUEL E. DOANE. 'Witnesses JOHN W. GIBBONEY, y BENJAMIN B. HULL.` 

